DANA D328 at Port Harcourt on Jan 23rd 2019, runway excursion on landing

Last Update: December 30, 2022 / 19:07:47 GMT/Zulu time

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Incident Facts

Date of incident
Jan 23, 2019

Classification
Incident

Cause
Runway excursion on landing

Airline
Dana Air

Flight number
DAV-462

Departure
Bonny, Nigeria

Destination
Port Harcourt, Nigeria

Aircraft Registration
5N-DOX

Aircraft Type
DORNIER 328

ICAO Type Designator
D328

A DANA Dornier Aviation Nigeria AIEP Dornier Do-328-100, registration 5N-DOX performing flight DAV-462 from Bonny to Port Harcourt (Nigeria) with 12 passengers and 4 crew, was on final approach to Port Harcourt's runway 22, winds from 250 degrees at 6 knots, runway was wet, about 6nm before touchdown when both power levers were at Flight Idle, the torque of the left hand engine indicated 24, the right hand engine however 20%. The aircraft continued for a touchdown to the right of the runway centerline, after the power levers were placed into the ground idle position the crew observed the left engine's torque at 27% and the right engine's torque at below 10%. After touchdown the captain took control of the aircraft. The aircraft veered further right to the runway edge and could not be controlled. In an attempt to stop the aircraft the first officer set the emergency brakes and put the condition levers to minumum and feather position. The aircraft went beyond the right runway shoulder 1190 meters/3900 feet down the runway, the number 4 tyre impacted a runway edge light while the aircraft travelled along the runway shoulder, the aircraft went over grass about 105 meters further down the runway, entered the apron after rolling on grass for 259 meters and came to a stop 3 meters short of the airport perimeter fence at the Aero Contractors ramp. No injuries occurred, the aircraft sustained minor damage.

Nigeria's Accident Investigation Bureau (NAIB) rated the occurrence a serious incident, opened an investigation and released their preliminary report on Apr 15th 2019.

The NAIB reported the techlog entries after landing mentioned that the left hand propeller would not come out of feather and tyres #1, #2, #3 and #4 had flat spots. The left hand engine's PCU was identified defective and was replaced on Jan 24th 2019, the PCU was sent for further tear down examination by the manufacturer. All 4 wheel assemblies were replaced.

On Dec 30th 2022 the NAIB released their final report concluding the probable causes of the serious incident were:

Asymmetrical propeller torque experienced on ground during landing roll due propeller Control Unit (PCU) failure in-flight.

Contributory factor

1. Non-recognition of the prevailing torque oscillation malfunction.
2. Non-execution of the proper checklist.
3. Excessive rudder application of -30o after landing.

The NAIB analysed:

General

The crew were certified and medically fit to operate the flight. The incident flight was the first flight of the day.

The aircraft documents and records available to the Bureau show that the aircraft was certified and maintained in accordance with approved procedures and existing NCAA regulations. There was no evidence of deferred defects or malfunctions in the aircraft technical logbooks that could have contributed to the occurrence at the time of departure from Finima, Bonny for Port Harcourt Military Airport.

This analysis focuses on the crew action during approach and landing phases of the flight, use of checklist, SOPs, evaluation of the tyre marks, tyre tracks and the Propeller Control Unit (PCU).

Conduct of the flight

At 09:58 h about 6 nautical miles to touchdown, the crew reported “RUNWAY IN
SIGHT” to DNPM ATC. The ATC reported the prevailing wind at 250o
/06 knots and runway 22 in use for landing. According to the crew statement, it was observed at short finals and with the power levers at flight idle position, the torque on engine number 1 and engine number 2 indicated 24% and 20% respectively. However, the crew account did not disclose any checklist action taken at the time of noticing this disparity in indication which should have called for “L or R PROP LOW PITCH”, (ABNOM-9-10) CONDITION: PCU DETECTED LOW PITCH CONDITION (BLADE ANGLE BELOW FI and SEVERE TORQUE OSCILLATIONS)” checklist.

Situational awareness/Use of checklist

The disparity in engine torque according to the FDR had occurred at 6,000 ft, which became more pronounced at touchdown to a value of 300% disparity as shown on the FDR plot. However, from the crew statement, these values were missed. Because they missed the true nature of the problem, they were not able to execute the correct checklist to arrest the situation.

The crew action to continue the approach under a normal landing checklist instead of the ABNOM-9-10 checklist was inappropriate. The crew should have discontinued the approach and pick a hold over the station to execute the applicable checklist before coming in to land.

Pilot’s radio communication with the ATC was not standard. He reported that he was “right base of left base of runway 22” while he was not at the airport’s circuit altitude, which did not convey his exact position.

The investigation revealed certain lapses in crew adherence to checklist application and SOP compliance in this flight.

Evaluation of tyre marks and tyre tracks

The tyre tracks showed that the aircraft landed right of the runway centerline and veered further right into the grass verge. This indicates the effect of a propeller torque asymmetry coupled with excessive rudder input of -30o as revealed by the FDR plots especially after touchdown which the crew were unable to arrest.

The investigation believed that there was a delayed application of Emergency brakes considering the distance travelled by the aircraft before it finally stopped.

Propeller Control Unit (P.C.U.)

5N-DOX landed to the right of runway 22 centerline. During the landing roll, with the power levers at ground idle position; torque on engine number 1 was 27% and increased to 34%. The torque on the engine number 2 decreased below 10%.

The disparity in the left and right propeller torque values is an indication of failure of the propeller control unit (PCU) of the number 1 engine. This is evident from the crew account that the engine number 1 torque value at about 6.2 NM to touchdown and at landing, did not agree with the corresponding power lever settings.
Incident Facts

Date of incident
Jan 23, 2019

Classification
Incident

Cause
Runway excursion on landing

Airline
Dana Air

Flight number
DAV-462

Departure
Bonny, Nigeria

Destination
Port Harcourt, Nigeria

Aircraft Registration
5N-DOX

Aircraft Type
DORNIER 328

ICAO Type Designator
D328

This article is published under license from Avherald.com. © of text by Avherald.com.
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